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Title: Identifying trends for understanding the role of humic substances in the environmental behavior of radionuclides

Humic substances are expected to have a major role in the environmental speciation of radionuclides. If the speciation of the radionuclide humic complex can be adequately modeled, predictions of its fate and transport may be possible. Additionally, humic substances have been shown to adsorb to a variety of mineral surfaces. The humic coated surfaces also interact with aqueous radionuclides, complicating environmental behavior. Studies indicate the importance of pH, ionic strength, and humic substance concentration in understanding the impact of humic substances on radionuclide speciation. However, values obtained to describe complexation or sorption vary and are difficult to compare and incorporate into existing geochemical codes due to variations in humic complexation models or concepts. This obscures intercomparison and the utility of the resulting values. This work shows results based on different concepts can be evaluated with the charge neutralization model, yielding similar stability constant values. The consistent stability constants found with the charge neutralization model can be used for intercomparison and identification of behavioral trends. A speciation calculation of a contaminated site using identified trends between humic and fulvic acid are given. The results yield good agreement between calculation and environmental observations. Laboratory experiments validate the identified trend. Comparisons between aquaticmore » and sorb humic acid are presented and similarities useful for modeling are given.« less
Authors:
;
Publication Date:
OSTI Identifier:
20015855
Resource Type:
Conference
Resource Relation:
Conference: 1998 Materials Research Society Fall Meeting, Boston, MA (US), 11/30/1998--12/04/1998; Other Information: Single article reprints are available from University Microfilms Inc., 300 North Zeeb Road, Ann Arbor, Michigan 48106; PBD: 1999; Related Information: In: Scientific basis for nuclear waste management XXII. Materials Research Society symposium proceedings: Volume 556, by Wronkiewicz, D.J.; Lee, J.H. [eds.], 1355 pages.
Publisher:
Materials Research Society, Warrendale, PA (US)
Research Org:
Massachusetts Inst. of Tech., Cambridge, MA (US)
Country of Publication:
United States
Language:
English
Subject:
54 ENVIRONMENTAL SCIENCES; HUMIC ACIDS; RADIONUCLIDE MIGRATION; SORPTIVE PROPERTIES; WASTE-ROCK INTERACTIONS; FULVIC ACIDS; CHELATING AGENTS; GROUND WATER; SENSITIVITY ANALYSIS